It seems there’s a consensus among those experiencing the “400 MHz bug” that it is specific to the Framework Laptop 13 12th Gen Intel and that all 12x0P mainboards share the defect (so, not a bad batch but a design fault).
Assuming that’s the case, I see three possible scenarios:
- It is caused by a bug in the firmware developed by Framework → could be solved by a update of the BIOS and/or EC.
- It’s a design fault in the Intel CPU that’s mitigated by other (more experienced) laptop manufacturer in hardware → that means users of a Framework laptop are out of luck.
- It’s a design fault in the Intel CPU that’s worked around in firmware by other (again more experienced) laptop manufacturers → there might be a chance that Framework eventually finds a fix that ends up in an UEFI or EC update.
Finding a common trigger for the 400 MHz bug might help to prevent it (or at least reduce the frequency) as long as there’s no proper solution. I’ve created Framework Laptop 13 Intel 12th Gen: Stuck on 400 MHz or not? to collect some information.